Since polyphenylene ether-based resins have a lightweight and are excellent in impact resistance as compared with metal or glass, the resins have been employed in a variety of fields including automobile parts, household electric appliance parts, and office automation equipment parts. However, since polyphenylene ether resins have a bad moldability, the resins are used not singly but as a mixture with a polystyrene-based resin which is completely compatible. However, the incorporation of the polystyrene-based resin which is more flammable than the polyphenylene ether-based resins lowers the heat-resistant temperature of the mixed resin of polyphenylene ether/polystyrene, and also makes the resin flammable. Therefore, a novel method that enables molding a polyphenylene ether-based resin without incorporating polystyrene has been desired. Moreover, it has been also desired to develop a method of achieving both moldability and flame resistance at the same time.
As methods for imparting flame resistance to polyphenylene ether-based resins, there have been known methods of adding a halogen-based, phosphorus-based, inorganic or a mixed retardant thereof, and thereby flame resistance has been imparted to some extent. Recently, however, a request for safety against fire has become particularly important and, at the same time, it has been strongly desired to develop a technology having no environmental problems. Therefore, it has been currently desired to develop a novel non-halogen or non-phosphorus flame retardant which exhibits a high flame-retarding effect and does not deteriorate practical performance such as mechanical properties of resin compositions. An organic silicon-based flame retardant is proposed as a flame retardant which possibly satisfies these requirements. As examples thereof, a flame-resistant resin compositions containing a polyphenylene ether-based resin composition and dimethylsilicone are disclosed in JP-B-63-10184, JP-A-64-4656, U.S. Pat. Nos. 4,497,925 and 4,387,176, and JP-A-2-133464. However, the silicone in the above publications has a low compatibility with polyphenylene ether-based resins and a low moldability. Moreover, the silicone cannot withstand practical use owing to its volatility.
In consideration of such situation, it is an object of the invention to provide a polyphenylene ether-based resin composition having none of the aforementioned problems, i.e., having an excellent melt flowability and flame resistance and a high heat resistance.